1. Field of the Invention
An object of the present invention is a system of optical connectors, namely a system of connectors used for to interconnect optical fiber sections. The aim of the invention is to enable the easy mounting and dismounting of the optical connectors contained in such a system, while at the same time providing for the easy mounting of the optical contacts themselves to the ends of the cables, the optical contact being then inserted into these optical connectors
2. Description of the Prior Art
There is, in particular, a known optical contact in the prior art mounted at one end of a cable and having at least one elastic strip or clip on an external rim. In a preferred embodiment, the contact has several elastic clips positioned evenly and symmetrically with respect to an axis of symmetry of the cable. These elastic clips extend slightly beyond the external rim of the contact and may be folded down against this contact when the optical fiber is inserted into a channel of a complementary connector. When the contact is inserted into the channel, the clips are stressed beforehand against the external rim of the contact. Then, when the contact has been plunged in to the maximum extent, for example when it stops against shoulder of the channel, the channel is designed in such a way that it has a hollow with a greater diameter wherein the elastic clips can get freely released. Once the elastic clips are released, they come to rest against a ring formed by this widening. The released elastic clips and the ring co-operate to prevent the optical fiber from coming out of the channel.
In the prior art, to bring the optical fiber out of this channel, a specific tool has to be used. The tool used folds down the released clips, being inserted from a connection face of the connector while the contact is inserted from a rear face. The tool used corresponds to a hollow cylinder sliding along the contact in the channel so as to stress the elastic clips along the external rim of the contact. Once these elastic clips have been folded down along the body, this contact can be withdrawn by the exertion of a tensile force on the optical face that extends beyond the rear face side of the connector.
This approach poses a problem. It may be dangerous to use a tool to obtain the exit of the optical fiber from the connector. Indeed, there is a risk that the tool might damage the connection end of the contact when it is inserted into the connection front face side. Furthermore, this approach entails a substantial space requirement. In particular it necessitates the obligatory and total disconnection of its complementary connector, for the disconnection tool is inserted from this connection front face of the connector.
In the prior art, there is the known teaching of the document EP-A-0 366 346 which describes a connector assembly comprising an optical contact mounted at one end of a cable and a complementary connector to receive this cable. The optical contact is inserted from a rear face into the connector. It has a ferrule and a sleeve mounted around the ferrule to associate this ferrule with the end of the cable. The ferrules essentially fulfill a mechanical grasping function to grasp the brittle end consisting of the optical fiber contained in the cable. Furthermore, the optical contact comprises a rear part around the cable. This rear part consists of an extension of the sleeve.
A fastening means with an elastic clip is mounted around this rear part. The rear part represents a section of the sleeve with a smaller diameter. According to this document, the complementary connector has a slot on the outer rim. The elastic clip extends beyond this slot when it is inserted therein. It is therefore no longer necessary to disconnect the connector from its complementary connector in order to withdraw an optical contact. On the contrary, this approach raises problems of tight sealing in the channel in which the contact is placed.
On the whole, this prior art approach raises a first problem because it always imperatively necessitates specialized tooling in order to be able to disengage an optical contact of this kind from a channel of the connector into which it is inserted. Indeed, the elastic clip co-operates with the groove of the channel from which it cannot come out without the exertion of pressure on the edges of this clip which extends beyond the slot on one side or the other.
The solution described here about raises a second problem owing to the fact that the catching system is a small part mounted on the sleeve. This part is necessarily held back in translation in order to prevent it from being lost or damaged during handling. Now, since the sleeve is fixedly joined throughout its length with the optical cable that it surrounds, the mobility of this part is limited. This makes it necessary to plan either for either very long sleeves which are difficult to mount or for handling operations in this very limited space just at the level of the connector.
This approach finally raises a third problem because, to be able to accurately fit the elastic clips into the groove of a channel of the complementary connector, it is necessary to place them so that they face each other. For this purpose, the fastening means has a longitudinal strip forming an added thickness on an external rim, to co-operate and thus orient the fastening means in the channel. Indeed, this strip must get inserted into a slot designed in the rim of the channel. The fitting in of this strip into the slot requires a rotational motion in order that it may be accurately presented. Now, if this handling has to be done by means of a set of tools, then the teaching of this document does not make it possible, any more than the other approaches of the prior art, to resolve the problem of the easy mounting of an optical contact in its complementary connector.
In the prior art, there are known fastening means that can be used manually and do not require the use of specialized tooling whether for mounting or for dismounting. Such means include, for example, the bayonet device as described in the document U.S. Pat. No. 4,738,508. According to this document, the bayonet is designed in such a way that the optical contact has a sleeve provided with a slot at the end of the optical cable. The slot designed to receive a pin on the periphery of the outer wall of a complementary connector of the contact. However, this approach raises a problem because to ensure that the contact is kept in the connector, the contact additionally has a second internal pin extending radially with respect to the optical fiber and having to co-operate with a slot made in the inner wall of the complementary connector. Indeed, this assembly requires excessively painstaking handling of the contacts and complementary connectors.
Finally, despite all the precautions, it would seem that, after a certain period of use, an optical connector of this kind is the site of transmission losses. It is therefore necessary to change or clean the optical fibers. This cleaning is difficult, given the penetration depth of the ends of the optical fibers, especially in female contacts. The easy withdrawal of the optical fiber from its connector enables easier cleaning and above all individual cleaning on the basis of identified needs without requiring a total dismounting of all the optical contacts.
The aim of the invention is to overcome these problems by proposing an optical contact such that an optical cable can be mounted and dismounted therein and furthermore such that this optical contact is itself easily to mount and dismount in a connector in which it may be placed. The solution of the invention enables mounting and dismounting by hand. Indeed, in the invention, it is planned especially that the rear part with the catching means will be easy to grasp and will slide along the optical cable. In sliding, the rear part can come close to the end of the cable where the ferrule and the sleeve are mounted. The fact that these parts come closer to each other also enables the insertion of the rear part into the channel of the connector which already receives the ferrule, the sleeve and the cable. This rear part then cooperates by rotation with a complementary recess designed on an inner wall of the channel to retain the contact totally within the connector.
Another advantage of the invention is that it procures tolerance of variations related to the expansion of materials, especially when they are placed in severe climatic conditions. This tolerance comes from the fact that the rear part is not directly attached to the cable but is really a sliding part.
In the preferred embodiment, to ensure tight sealing at this rear sliding part, this part has at least two seals: an internal seal between an inner wall and the cable, and an outer seal between an outer wall and an inner wall of the channel of the connector in which the contact is mounted. Since these seals are preferably O-rings, they do not hamper the mobility of the rear part along the cable.
An object of the invention therefore is an optical contact mounted around an optical cable, the optical contact comprising a ferrule mounted at one end of the cable, a sleeve fixedly holding the cable and the ferrule, and a catch mounted around the cable and designed to co-operate with a complementary connector in order to hold the optical contact therein in a channel of the complementary connector, wherein the catch is mounted on a rear part of the contact and this rear part slides along the cable, the catch being capable of being engaged by rotation in the inner wall of the channel.